Control system for a cigarettemaking machine



April 7, 1970 w ow 3,504,679

CONTROL SYSTEM FOR A CIGARETTE-MAKING MACHINE Filed June 8. 1960 2 Sheets-Sheet 1 INVENTOR April 7, 1970 w. B. LOWMAN 3,504,679

CONTROL SYSTEM FOR A CIGARETTE-"MAKING MACHINE Filed June 8. 1960 2 Sheets-Sheet 2 INVENTOR Wale/f 58025101026141) United States Patent 3,504,679 CONTROL SYSTEM FOR A CIGARETTE- MAKING MACHINE Walker B. Lowman, Columbus, Ohio, assignor to Industrial Nucleonics Corporation, a corporation of Ohio Filed June 8, 1960, Ser. No. 34,748 Int. Cl. A24c 5/34 U.S. Cl. 13121 3 Claims This invention relates to cigarette manufacture, and more particularly it relates to improvements in a system for automatically controlling the weight per unit length of the cigarette rod formed by a continuous cigarettemaking machine.

In a relatively new type of cigarette-making machine, a stream of tobacco is delivered to a point near the entrance of the cigarette rod forming apparatus. The weight per unit length of said stream is arranged to be somewhat in excess of the desired weight per unit length of the tobacco filler within the wrapped cigarette rod. Specifically, the excess is desirably large enough to encompass all the unavoidable variations which occur as the stream is being formed from cut tobacco. Thereupon, at the'point aforesaid, the excess tobacco in the stream is removed. In a preferred type of removal device, removal of the excess is effected by a rotating knife which slices off the top layer of the stream, and in theory thereby removes most of the lumps, bunches and other irregularities in the stream which would otherwise appear in the finished cigarette rod. Means are provided for adjusting the depth of the knife relative to the channel which carries the stream, and it has been proposed that the knife position be automatically controlled in response to measurements of the cigarette rod.

The knife position control device aforesaid, on a machine of the type described, has an inherent theoretical advantage over the conventional feeder control systems now in use. This advantage obtains by reason of the short transportation delay, that is, the time required for the stream leveled by the knife to be formed into the cigarette rod and measured by the gauge. However, the theoretically possible improvements in cigarette quality have not been achieved in practice.

In retrospect, it is now known that much of the difficulty previously encountered was the result of non-uniformity of the feed. Previously, the operation of the tobacco feed mechanism, which determines the rate at which the tobacco was fed to the stream, was regulated to some extent by utilizing limit switches actuated on overtravel of the knife position adjusting mechanism. Thus when the knife adjustment reached a point near the limit of travel, an incremental increase or decrease in the speed of the tobacco feed mechanism would result.

In accordance with his invention it has been found that the effectiveness of the knife control is much more dependent on slight variations in the tobacco feed than had heretofore been realized. That is to say, it appears that there is an optimum value of the weight per unit length of the tobacco stream which is presented to the equalizer knife for leveling thereby. Moreover, this optimum value is subject to variation depending on the individual machine and the physical characteristics of the tobacco to be processed.

Further in accordance with this invention it lxs been found that the return flow of the aforesaid excess tobacco removed from the main stream is a useful indicator of the performance of the tobacco feed mechanism. This is particularly true in the case of one previously known type of cigarette-making machine more fully described hereinafter, wherein the excess stream of tobacco is returned forthwith by conventional means to the primary stream which has been metered out by the feed mechanism. Hence I provide an automatic feed control system responsive to direct measurements of the return flow of tobacco. As one feature thereof, the invention provides novel gauge arrangements for measuring the flow of tobacco caried by a carded drum.

The feed control device is utilized as one stage in an overall cigarette maker control system which also includes means responsive to the weight per unit length of the cigarette rod for controlling the position of the knife. The knife control is designed to operate with a high velocity constant, taking full advantage of the short transportation delay to level out the short term variations in the stream, whereas the feed control maintains the unleveled stream at an optimum value of weight per unit length such that the knife control is enabled to operate in its most effective range. Because the tobacco cut off by the knife is recirculated by adding it to the stream of tobacco supplied from the feed mechanism, any persistant variation in this stream from the feed mechanism is amplified. That is, any excess supply keeps accumulating, and any shortage accumulates until there is virtually no tobacco in the return flow. Since small errors in the feed mechanism cause a large cumulative error in the return flow, no great accuracy or stability is required of the measuring device for the return flow, which can be of a type which is simple, inexpensive and capable of installation with a minimum of modification of a cigarette-making machine.

Therefore, it is the object of this invention to provide a new and improved control system for cigarette-making machines whereby short term variations as well as mean value variations in the weight per unit length of the cigarette rod are substantially reduced.

It is also an object to provide, in combination with a machine for forming a stream of tobacco and a device for removing a variable portion of said stream, a control system including means for automatically adjusting said removal means to maintain the remainder of said stream at a substantially constant weight, and means for automatically adjusting said stream forming means whereby the stream is continuously adapted to be operated on by said removal means in the most effective manner.

It is another object to provide novel means for measuring the flow of cut tobacco on a carded drum.

It is still another object to provide, in cigarette-making apparatus having means for forming a tobacco stream, means for removing the excess in said stream and means for forming the remainder of said stream into a cigarette rod, an improved system for automatically controlling the stream forming means in accordance with direct measurements of said excess.

Further objects and advantages will become apparent in the following detailed description of one preferred embodiment of the invention, taken in connection with the appended drawings, in which:

FIG. 1 is a simplified schematic showing of a cigarettemaking apparatus having a control system in accordance with the invention.

FIG. 2 is a more detailed showing, in elevation, of a portion of the apparatus of FIG. 1.

FIG, 3 is a fragmentary sectional view taken on the line 3-3 of FIG. 2.

FIG. 4 is a fragmentary sectional view showing hoW anolther type of measuring device may be adapted for use in the control system of FIG. 1.

FIG. 5 is a fragmentary sectional view showing how still another measuring device may be adapted for use in the system of FIG. 1.

Referring now to the drawings, FIG. 1 is a simplified schematic showing of a specific type of cigarette-making machine, for example, a machine such as the Garant 3 Twin Rod Spiral Machine which is manufactured by Hauni Werke Korbe & Company, KG., Hamburg, Germany. Herein the numeral indicates a conventional feed mechanism which showers cut tobacco onto a horizontal belt 12 passing under a first drum 14 having a peripheral groove (no shown).

The tobacco on belt 12 is pressed into the groove in drum 14 and retained therein by partial vacuum, supplied through the hollow interior of the drum, The tobacco stream is carried over the drum and under a rotating equalizer knife 16. The leveled tobacco stream 18 is then transferred to the usual traveling paper web 20 and carried thereon by the usual tube belt 22 into the rod former 24 which forms the cigarette rod 26.

The excess tobacco 28, including most of the bunches and irregularities in the tobacco stream carried over drum 14, is received by a second, carded drum 30 rotating in the same direction as drum 14 but at a different speed. A picker roller 32 coacting with drum 30 removes the tobacco 28 therefrom, and the same is forthwith returned to belt 12 to merge with the tobacco supplied from the feeder 10.

The equalizer knife 16 is adjustable through a distance of about one millimeter toward and away from the drum 14 through a lever system 34 including a cam 36 and follower 38 device. In accordance with this invention the position of the cam 36 is continuously readjusted by a measuring and feedback control system comprising a suitable gauge transducer 40 responsive to the weight per unit length of the rod 26, an amplifierom troller device 42-44, and a servo motor 46 and gear box 48 for driving the cam 36. The gauge-controller system 40-48 is preferably of the type described in the copending application of Philip Spergel and Sidney A. Radley, Ser. No. 641,414, filed Feb. 20, 1957, now Patent No. 2,955,- 206 issued Oct. 11, 1960. The gauge transducer 40 preferably comprises a radiation source 40a and a radiation detector 40b in an arrangement somewhat as described in the copending application of Sidney A. Radley and Philip Spergel, Ser, No. 641,357, filed Feb. 20, 1957, now Patent No. 2,954,775 issued Oct. 4, 1960. As is set forth in said Ser. No. 641,414, the control system employs a tachometer 46a coupled to or integral with the servo motor and forming part of an internal feedback loop whereby the control system functions as a special analog device for computing the time integral of the error in weight per unit length of the cigarette rod 26 and repositioning the cam 36 in accordance with the value of said integral.

Further in accordance with the invention there is provided means for measuring the return flow of excess tobacco 28 around the drum 30. In one preferred from of the invention as illustrated a dielectric gauge is employed for this measurement. This gauge includes a curved capacitor plate 50 spaced from the carded drum 30 and connected through a cable 52 to suitable capacitance measuring circuits 54. The capacitance measuring system 54 may be any of several types well known in the art which are adapted to provide a suitable signal to a controller 56. The controller 56 includes circuits for actuating a motor 58 which is connected through a gear box 60 and suitable mechanical drive arrangement represented by the dotted line 62 to the control shaft 64 of the feeder mechanism 10. The feeder 10 is driven by a variable speed mechanism in a manner similar to that which is described and illustrated in the above-referenced application Ser. No. 641,357, the angular position of shaft 64 thereby determining the rate at which the feeder deposits tobacco on belt 12. The controller 56 may be of the same type as the controller 44, in which case the motor 58 is equipped with a tachometer 58a, Alternately, the controller 56 may be of the type which is illustrated in FIG. 2 of Patent No. 2,895,888, in which case the tachometer 58a is omitted.

In order to visualize the operation of the knife control,

first assume that an optimum stream of tobacco is flowing on belt 12, that the knife 16 is in, say, the center of its positional range and that the cigarette rod 26 has the correct weight per unit length. Under these conditions no action is taken by the control system. Now if for some reason the rod 26 becomes light, say, the controller 44 will raise the knife 16, allowing more tobacco to pass into the rod former 24 but returning less tobacco around drum 30 to belt 12. It is apparent that the return flow 28 of tobacco constitutes a small reservoir which can be manipulated by the equalizer knife control so as to iron out medium or short-term variations in the feed.

If it is the case that the light condition of the rod aforesaid results from an insufficiency in the mean flow of tobacco on belt 12, the knife control action becomes regenerative. That is, the raising of the knife results in less return flow 28, which in turn decreases the amount of tobacco carried by drum 14, requiring a further raising of knife 16 by the controller, still further decreasing the return flow 28, and so on.

If this situation were to continue, the stream of tobacco on drum 14 would soon become so sparse that the irregularities in the stream could not be effectively removed by knife 16, which would only skim off the tops of the lumps and bunches therein, resulting in the production of cigarettes having excessive weight variane.

An opposite sequence of operation occurs in the event that the stream of tobacco from the feeder is excessive, eventually resulting in choking of the return flow system.

It is now apparent that the regenerative behavior of the knife control device, in maintaining constant the mean weight of the cigarette rod when an improper tobacco feed rate obtains, is reflected in the return flow of tobacco around drum 30. That is to say, a relatively slight but persistent error in the rate of feed is manifested as a relatively large variation in the return flow 28, the feed rate variation being virtually amplified in the return flow variation by the action of the knife control system.

In the past many attempts have been made to measure the flow of loose tobacco, or tobacco carried by a belt or carding drum. To the best of applicants knowledge none of these schemes has been successful, for the simple reason that these measurements cannot be made very accurately. However, in the present control system, for the reason set forth it is found that the device used to measure the return flow 28 of tobacco on drum 30 does not need to be particularly accurate or stable, and hence any one of several prior art measuring devices, suitably modified, can be used for this purpose.

FIGS. 2 and 3 show details of a capacitance gauging head for measuring the return flow of tobacco. The capacitor plate 50 of FIG. 1 comprises a metal shoe 50a which is preferably imbedded in an integral sheath 5% of molded polytctrafluoroethylene resin, as is marketed under the trademark Teflon, and secured to the frame of the machine by suitable insulating supports as at 70. The Teflon sheath presents an anti-friction, anti-gurnming surface to the tobacco 28 passing thereunder, while its insulating quality eliminates spurious signal variations due to contact conductance.

The other capacitor plate is provided by a modification of the carded drum 30 which carries the return flow 28 of tobacco. The drum is conventionally constructed with a leather or canvas facing 72 having a plurality of rows of carding points as at 74 resembling bent carpet tacks extending therethrough. In accordance with one feature of the present invention, a plurality of hoop-like metal bands as at 76 are compressively secured around the periphery of the facing between the rows of carding points. The bands are preferably constructed of thin metal strip material such as shim stock having an extruded sheath of Teflon plastic which serves to electrically insulate the metal strips from the hygroscopic facing and thereby minimize leakage currents through the ground capacitance of the machine. The bands 76 are electrically connected together as indicated by the wire loops as at 78, and are further connected by fiat insulated conductors as at 80 to a contact button (not shown) mounted in a phenolic insulating disc 82 secured to drum 30 at the hub axis thereof. The lead wire 52a to the measuring circuits 54 is connected to a spring loaded contact brush 84 which bears against the rotating contact button.

In the operation of the feed control system it is apparent that an increase in the return flow 28 of tobacco around the drum 30 results in an increase in capacitance between the shoe 50a and the revolving bands 76, whereas a decrease in the return flow results in a decreased capacitance therebetween. In a well-known manner similar to the operation of the electrodes described in US. Patent No. 2,729,213 to W. C. Broekhuysen et al., in providing a signal for a controller, capacitance changes are utilized by the measuring circuits 54 to provide suitable error signals to controller 56, whereby predetermined variations in the return fiow 28 result in actuation of the motor 58 in one direction or the other to reset the control shaft 64 of the variable speed transmission (not shown) driving the feeder 10, thus restoring the rate of flow of tobacco on the feed belt 12 to the proper value.

It is apparent that other devices for measuring the return fiow 28 of tobacco can be employed. For example, as is shown in FIG. 4, a light source 90 may be used to direct a beam of light, along a line 92 properly spaced from the periphery of drum 30, toward a photoelectric detector 94. Since the light beam is variably attenuated by the return fiow 28 of tobacco in accordance with the amount thereof carried by the drum 30, the signal output of detector 94 may be employed to control the feeder 10.

In FIG. 5 it is seen that a beta ray backscatter measuring device can also be employed. In this device the measuring head comprises an ionization chamber 96 having a radioactive beta radiation source holder 98 mounted therein to direct a beam of beta radiation radially toward the carded drum 30. The theory of operation and further constructional details of the backscatter head are more fully described in the aforesaid Patent No. 2,895,888. In adapting this system to the measurement of tobacco on the drum 30, it is proposed that bare metal bands 100 be mounted on the drum, extending continuously around the same and joined together between rows of teeth so as to aiford the smallest possible exposure of the carding cloth to the beta radiation beam. Thus good contrast is achieved in accordance with the principles set forth in said patent, and the efiects of variations in the drum facing are minimized.

Suitable, spring-loaded mechanical or electro-mechanical feeler gauges, working between the carding points, can also be used to measure the thickness of the return flow tobacco on the drum 30.

What is claimed is:

1. For use in a cigarette-making machine which includes adjustable stream forming means for forming a primary tobacco stream, means defining a final tobacco stream whence a cigarette rod is formed, conveying means between said primary and final streams, and a removal means adjacent the conveying means, said conveying means including a forward feeding conveyor for conveying tobacco from a discharge end of the primary stream to said removal means, said removal means acting to divide the tobacco reaching it into said final stream and an excess stream, and said conveying means further including a return feed conveyor for receiving the excess stream and conveying it to the discharge end of the primary stream adjacent the upstream end of the conveying means:

apparatus for maintaining a substantially constant rate of flow of tobacco in said excess stream, which apparatus comprises (a) a first detector disposed adjacent said final stream for measuring the amount of tobacco per unit length in said final stream,

(b) means responsive to said first detector for controlling said removal means to adjust the portion of the flow from said forward feeding conveyor which is diverted to form said excess stream and to maintain the amount of tobacco per unit length in said final stream substantially constant,

(c) a second detector disposed adjacent said return feed conveyor for measuring the amount of tobacco in said excess stream,

(d) means responsive to said second detector for controlling said adjustable stream forming means to maintain substantially constant the rate of flow of tobacco in said excess stream as formed by said removal means,

(e) said removal means including a carded drum for returning said excess stream to said primary stream, and wherein said second detector comprises gauging means mounted adjacent said drum for measuring the amount of tobacco carried thereby, and

(f) said carded drum including a facing peripherally mounted thereon, a plurality of carding points projecting from said facing, and means providing a metal surface at least partially overlying said facing, said metal surface being operatively associated with said gauging means.

2. Apparatus as in claim 1 wherein said gauging means includes an ionizing radiation source mounted adjacent said carding drum for directing a beam of radiation into said metal surface, and means for quantitatively detecting radiation reflected from said surface and returned backwardly through said excess flow of tobacco carried by said drum.

3. Apparatus as in claim 1 wherein said gauging means includes a metal shoe mounted adjacent said carded drum and spaced therefrom, and means for measuring the electrical capacitance between said metal surface and said shoe.

References Cited UNITED STATES PATENTS 3,130,733 6/1960 Martin. 3,132,650 5/1964 Richter. 2,815,759 12/1957 Molins et al. 2,519,089 8/ 1950 Whitaker. 2,729,213 1/ 1956 Broekhurpen et al. 1,864,728 6/1932 Hawkins. 2,163,415 6/ 1939 Stephano. 2,93 8,521 5/1960 Lanore. 2,660,178 11/1953 Rault 13184 FOREIGN PATENTS 956,568 1/ 1957 Germany. 795,533 5/1958 Great Britain. 1,233,540 5/1960 France.

217,773 10/ 1958 Australia.

JOSEPH S. REICH, Primary Examiner US. Cl. X. R. 

1. FOR USE IN A CIGARETTE-MAKING MACHINE WHICH INCLUDES ADJUSTABLE STREAM FORMING MEANS FOR FORMING A PRIMARY TOBACCO STREAM, MEANS DEFINING A FINAL TOBACCO STREAM WHENCE A CIGARETTE ROD IS FORMED, CONVEYING MEANS BETWEEN SAID PRIMARY AND FINAL STREAMS, AND REMOVAL MEANS ADJACENT THE CONVEYING MEANS, SAID CONVEYING MEANS INCLUDING A FORWARD FEEDING CONVEYOR FOR CONVEYING TOBACCO FROM A DISCHARGE END OF THE PRIMARY STREAM TO SAID REMOVEL MEANS, SAID REMOVAL MEANS ACTING TO DIVIDE THE TOBACCO REACHING IT INTO SAID FINAL STREAM AND AN EXCESS STREAM, AND SAID CONVEYING MEANS FURTHER INCLUDING A RETURN FEED CONVEYOR FOR RECEIVING THE RECESS STREAM AND CONVEYING IT TO THE DISCHARGE END OF THE PRIMARY STREAM ADJACENT THE UPSTREAM END OF THE CONVEYING MEANS: APPARATUS FOR MAINTAINING A SUBSTANTIALLY CONSTANT RATE OF FLOW OF TABACCO IN SAID EXCESS STREAM, WHICH APPARATUS COMPRISES (A) A FIRST DETECTOR DISPOSED ADJACENT SAID FINAL STREAM FOR MEASURING THE AMOUNT OF TOBACCO PER UNIT LENGTH IN SAID FINAL STREAM, (B) MEANS RESPONSIVE TO SAID FIRST DETECTOR FOR CONTROLLING SAID REMOVAL MEANS TO ADJUST THE PORTION OF THE FLOW FROM SAID FROWARD FEEDING CONVEYOR WHICH IS DIVERTED TO FORM SAID EXCESS STREAM AND TO MAINTAIN THE AMOUNT OF TABACCO PER UNIT LENGTH IN SAID FINAL STREAM SUBSTANTIALLY CONSTANT, (C) A SECOND DETECTOR DISPOSED ADJACENT SAID RETURN FEED CONVEYOR FOR MEASURING THE AMOUNT OF TOBACCO IN SAID EXCESS STREAM, (D) MEANS RESPONSIVE TO SAID SECOND DETECTOR FOR CONTROLLING SAID ADJUSTABLE STREAM FORMING MEANS TO MAINTAIN SUBSTANTIALLY CONSTANT THE RATE OF FLOW OF TOBACCO IN SAID EXCESS STREAM AS FORMED BY SAID REMOVAL MEANS, (E) SAID REMOVAL MEANS INCLUDING A CARDED DRUM FOR RETURNING SAID EXCESS STREAM TO SAID PRIMARY STREAM, AND WHEREIN SAID SECOND DETECTOR COMPRISES GAUGING MEANS MOUNTED ADJACENT SAID DRUM FOR MEASURING THE AMOUNT OF TOBACCO CARRIED THEREBY, AND (F) SAID CARDED DRUM INCLUDING A FACING PERIPHERALLY MOUNTED THEREON, A PLURALITY OF CARDING POINTS PROJECTING FROM SAID FACING, AND MEANS PROVIDING A METAL SURFACE AT LEAST PARTIALLY OVERLYING SAID FACING, SAID METAL SURFACE BEING OPERATIVELY ASSOCIATED WITH SAID GAUGING MEANS. 